<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>19、生命周期</title>
</head>
<body>
    <div id="test"></div>

    <script type="text/javascript" src="../js/react.development.js"></script>
    <script type="text/javascript" src="../js/react-dom.development.js"></script>
    <script type="text/javascript" src="../js/babel.min.js"></script>
    <script type="text/javascript" src="../js/prop-types.js"></script>
    
    <script type="text/babel"> 
        class Life extends React.Component{
            death = () => {
                // clearInterval(this.timer)
                // 写在组件
                ReactDOM.unmountComponentAtNode(document.getElementById('test'))
            }
            state = {opacity:1}

            // 组件挂载页面之后调用
            componentDidMount(){
                this.timer = setInterval(() => {
                    let {opacity} = this.state
                    opacity -= 0.1;
                    if(opacity <= 0) opacity = 1
                    this.setState({opacity})
                },200)
            }

            // 组件将要被卸载
            componentWillUnmount(){
                clearInterval(this.timer)
            }

            // 挂载执行一次，每次state更新执行一次
            render(){
                return (
                    <div>
                        <h2 style={{opacity:this.state.opacity}}>React学不会怎么办</h2>
                        <button onClick={this.death}>不活了</button>
                    </div>
                ) 
            }
        }
        ReactDOM.render(<Life />,document.getElementById('test'))
    </script>
</body>
</html>